This invention relates to ultraviolet radiationcurable coating compositions. More particularly it relates to photopolymerizable coating compositions containing a phenacyl ester photosensitizer and a tertiary aliphatic amine, and to polymerized coatings obtainable therefrom.
It is well-known that polymerizable coating compositions can be cured by exposure to actinic radiation, such as ultraviolet light. In general, such compositions comprise (a) a photopolymerizable polyethylenically unsaturated compound and (b) a photosensitizer, with or without (c) a colorant. Various photosensitizers such as acetophenones, benzoin acetate, benzaldehydes, benzoins, and 2,2-dialkoxyacetophenones, used alone or in combination with a trialkylamine, have been used as initiators for photopolymerizations. See Leekley, et al., U.S. Pat. No. 3,081,168; Sandner, et al., U.S. Pat. No. 3,715,293 and Shur, et al., U.S. Pat. No. 3,772,062. Since none of the known photosensitizers has been found to be completely satisfactory, research continues in order to find compounds or mixtures which will be more satisfactory. The present invention arose out of such research and resulted in the discovery of novel photosensitizer compositions which are useful for the photopolymerization of radiation-curable compositions.